This invention relates to marine fenders, and more particularly to an improvement of a so-called cell-type marine fender comprising a hollow cylindrical body composed of rubber or rubbery elastic material, one end of which being provided with a securing flange for a quay wall and the other end of which being provided with a fitting flange for a shock receiving member, an annular rigid reinforcing plate embedded in each of both the flanges, and a fillet reinforcement provided on a foot portion of each flange in the hollow cylindrical body.
The cell-type marine fenders of this type exhibit a transition curve against berthing shock in the transverse bulging deformation of the hollow cylindrical body under a berthing load. This extends from a stage of reducing an increasing rate of reaction force through a stage of maintaining reaction force at a substantially fixed value or a so-called buckling deformation stage to a compression deformation stage produced at mutual contacting state of the inner surface of the hollow cylindrical body. This is shown by a solid line B in FIG. 1, and hence these devices have a largely high absorption energy, so that they are widely and favorably used in Japan and other countries.
In order to have an accurate occurrence of the above buckling deformation, however, there has hitherto been taken such a means that a pair of annular grooves are arranged near boundaries of an initial outward-bulging region in the hollow straight cylindrical body produced under a vertical load subjected thereto. FIG. 2 illustrates a conventional marine fender, wherein numeral 1 designates a hollow cylindrical body, numeral 2 a flange used for securing the fender or fitting a shock receiving member, numeral 3 an annular groove, numeral 4 an annular rigid reinforcing plate embedded in the flange 2, numeral 5 a fillet reinforcement provided on a foot portion of the flange 2, and numeral 6 a bolt hole for the flange 2.
The conventional cell-type marine fender takes a final posture at the compression deformation as shown in FIG. 3, from which it is apparent that straight cylindrical portions 1'a remain near both ends of the body 1 because the buckling deformation is restricted by the annular groove 3. After buckling deformation, the mutual contacting 7 of the inner surface of the body 1 is produced to transfer the deformation into such a simple compression deformation that the characteristic curve B of FIG. 1 rises steeply. That is, the conventional marine fender is compressed up to a value of subtracting a deformation quantity .delta..sub.1 from a height of the cell-type marine fender or a distance H between the outer surfaces of the flanges. Therefore, the deformation progress of the hollow cylindrical body 1 is disadvantageously restricted by the annular groove 3.